Interesting. We were pretty poor when I grew up in the 70s and 80s. Blue collar family, rented accommodation etc.
BUT. We lived in London, so galleries, parks, exhibitions were free ( or very cheap). I could read by the time I went to school as my family were prodigious readers. What I guess you'd call working class intelligentsia, to a degree. I was always at the library, the school library or swapping books with friends. I would read anything.
Discussions round the kitchen table, radio 4 on in the background, classical music as well as pop. Open University programmes on the telly. I went to Sunday school.
^
My father was the first person with a university education in our family ( he put himself through the Open University) when he was in his 40s. He went on to get a PhD. He didn't use it to further his career, he just enjoyed the mental challenge.^
^
I was never told that something wasn't suitable, so I read and watched things that were sometimes completely incomprehensible, but must have gone in at some level. I was lucky that my father would talk to me about anything. He was a self taught man but he was endlessly curious about the world around him.^
Like a PP, I was au fait with Mythology, the Classics, Biblical imagery and texts which made school a doddle. I wasn't academically inclined as I favoured the arts, but school ( comprehensive in a fairly run down area) was an absolute breeze in that respect. Not so maths, no-one in my family likes maths 
I have friends now who had the same working class upbringing as I did but whose parents were uninterested in the wider world and so didn't read, go to galleries or show any interest in politics.
My friends haven't been able to pass along the same wealth of knowledge to their children , and although they can afford to send their children to private schools, and pay for them to attend every class under the sun, join clubs and visit every gallery in existence, it doesn't always bear much fruit culturally or intellectually because intrinsically it's not of any interest to the parents, who are, to an extent, just 'buying' their education rather than sharing it with them.
Reading is key.